Photographic objective.



PATENTED AUG. 4, 1908.

P. RUDOLPH. PHOTOGRAPHIC OBJECTIVE.

APPLIOATION FILED JULY 12,1907.

Draftsman,

UNITED STATES PATENT OFFICE.

PAUL RUDOLIH, OF JENA, GERMANY, ASSIGNOR TO THE FIRM OF CARL ZEISS, OF JENA, I

GERMANY.

PHOTOGRAPHIC OBJECTIVE. i -l Specication of Letters Patent.

Patented Aug. 4, 1908.

Application led July 12, 1907. Serial No. 383,411.

To all whom it may concern:

Be it known that I, PAUL RUDOLPH, doctor of philosophy, a citizen of the German Empire, and residin at Carl-Zeiss strasse, Jena, in the Grand uchy of Saxe-Weimar, Germany, have invented a new and useful Photographic Objective, of which the following is a specification.

The present invention is an improvement in certain of the Zeiss double objectives described in the patent to Rudolph 444714.

It relates to that kind of objectives, the two components of which consist each of a collective lens and a dispersive lens, both lenses being cemented together, in the one component a dispersive cemented surface presenting its concavity towards the diaphragm, in the other component a collective cemented surface presenting its convexity towards the diaphragm, while in both components, or only in that one with the dispersive cemented surface, the dispersive lens has higher relative dispersion than the collective lens.

Thisimprovement consists in this, that the collective lens, which appertains to the dispersive cemented surface, is produced from a glass of relatively high refractive index, that is to say, one whose refractive index amounts to at least 1.54, consequently the height of the index should at least be that of a light flint glass. In all former constructions according to the said specification 444714 a glass of very low reractive index has been made use of for] this collective lens, in order to obtain an especially large dierence between the refractive indices at the dispersive cemented surface. Investigations, upon which the present invention is based, have, however, shown that the important point for the correction is not so much this difference but rather the height of the index of the collective lens.

The advantage of the new objective consists in, that relatively large apertures or small zones of spherical aberration or satisfactory iiatness of field can be obtained. This eifect of the present improvement is independent of whether the componentpossessing the collective cemented surface is composed of two or three lenses.

The annexed drawing shows an unsymmetrical double objective, in which the invention is realized.

objectives according to the present invention the relative aperture is 1212.5. The radii, thicknesses and distances refer to a focal length 100. The kinds of glass are characterized by the refractive indices nn and nG, of which nD relates to the D-line of the solar and nG to the I-Iy-line of the hydrogen spectrum. The relative dispersion is determined by the expression Example 1 (represented in the drawing It is only in the component with the dispersive cemented'surface, that the dis ersive lens has higher relative dispersion t an the collective lens.

Radii, thicknesses and distances.

Exam le 2: In both components the dispersive ens has higher relative disperslon than the collective lens.

Radii, thicknesses and distances.

I claim:

1. Unsymmetrical double objective, one component of which consists of a collective lens and a dispersive lens cemented together, the collective lens having the lower relative dispersion and the dispersive lens the higher one, the cemented surface being dispersive co ective ens amounting to at least 1.54, and the other component of which includes a collective cemented surface convex towards the diaphragm.

a d resenting its concavity towards the, @LSE and the refractive index of the? 2. Objective of tWo components, each conn id 4.- nd a relasisting of a collective lensand a dispersive tive dispersion Which is lower than that of 10 liens cemened together, C(inne fcomponent. the dispersive lens of the same component.

aving a co ective cemente sur ace convex 5 towards the dia hragm, the other compo- PAUL RUDOLPH nent having a dispersive cemented surface Witnesses: concave towards the diaphragm, and the col- PAUL KRGER, lective lens of this other component having e, FRITZ SANDER. 

